424 Mevietus — Geology of the Country around Lichfield. 



pre-Carboniferous rocks and the productive Coal-measures is revised 

 and brought up to date with modern mining information ; interesting 

 accounts are given of the structural features, particularly of the 

 boundary faults, and the modern subdivisions of the red rocks of 

 the Upper Coal-measures are described in very considerable detail. 

 With regard to the productive Coal-measures, an interesting fact is 

 that in the North Warwickshire field the lower coals have been found 

 to improve towards the north, and that there is now talk of reopening 

 old pits which were originally only sunk to the seven-feet coal higher 

 in the series and sinking them to these lower coals. With regard 

 to the Upper Coal-measures, a satisfactory subdivision comparable 

 with that well known in North Staffordshire has now been established 

 for this area. The Black-band Ironstone Group is absent, but the 

 Etruria Marls, with their characteristic Espley rocks, are of normal 

 type. The succeeding Halesowen Sandstone comprises two sub- 

 divisions, a lower series of sandstones and an upper one of marls 

 with Sjnrorbis limestones ; one of these, the " Index Limestone ", 

 at the base of the marls, and resting on a well-marked sandstone, is 

 of great value in mapping and determining the depths of the coals. 

 The Keele Beds are the normal red marls with Spirorhis limestones, 

 but are overlaid by 2,000 feet of red sandstones, the Hamstead Beds, 

 which seem to be deiinitely pre-Permian, and are therefore included 

 in the Coal-measures. The accurate recognition of horizons in these 

 rocks is a question of great importance, since the possibility or 

 otherwise of the presence of coal at workable depths may depend 

 entirely on the correctness of the diagnosis. As an instance of this, 

 the country between Tamworth and the Western Boundary Fault 

 of the North Warwickshire Coalfield may be quoted. Here rocks 

 which were originally mapped out as Keuper Sandstone have now 

 been proved, by the recognition of Spirbrbis limestones associated 

 with the peculiar rock-type known as Pellet Sandstone, to belong 

 to the Keele series. This determination allows a fairly definite idea 

 to be formed about the depth of the coal, whereas, on the former 

 mapping, no estimate could have been given owing to the great 

 unconformity existing between the Coal-measures and the Trias. 



Both the coalfields described are bounded on both sides by faults 

 of considerable downthrow. These faults show many points of 

 interest, and not the least of these is the great width of the disturbed 

 areas, which has been proved by the driving of exploratory headings. 

 One of these headings, driven through the Eastern Boundary Fault 

 of the South Staffordshire Coalfield, from the Walsall Wood 

 Colliery's workings, proved the disturbed area to be 350 yards wide, 

 while further south at Aldridge the belt of disturbance is 1,200 yards 

 wide. In the first of these explorations the heading left the Shallow 

 Coal and was driven for 75 yards through measures with broken 

 masses of coal, for the next 73 yards it passed through grey measures 

 much squeezed and compressed, dipping 24 degrees E.N.E. ; from 

 a distance of 148 yards to 350 yards from the starting-point the rock 



